Sternpost construction



Oct. 24, 1939. E. CHAPMAN STERNPOST CONSTRUCTION Original Filed Aug. 27,1934 2 Sheets-Sheet 1 Oct. 24, 1939. E. CHAPMAN STERNPOST CONSTRUCTIONOriginal Filed Aug. 27, 1934 2 Sheets-Sheet 2 jywenzor Patented Oct. 24,1939 UNITED STATES PATENT OFFICE Application August 27, 1934, Serial No.741,650

Renewed January 24, 1939 11 Claims.

My invention relates to ship construction and the object of my inventionis to provide an improved form of sternpost or rudder support, whichsternpost has been designed to resist the usual loads which tend to bendand twist the same.

Depending upon the size of the ship, these sternposts are of very greatweight. For instance, in a ship of ten thousand (10,000) tonsdisplacement, the sternpost may have a weight in excess of fifteen tons.

By reason of the duty imposed upon sternpost structures, it is necessarythat they be highly resistant to load stresses tending to bend and twistthe same. I'he predominant load on a 5, sternpost has a bending andtwisting tendency,

and the" principal object of my invention is to provide a structure inwhich the resistance to bend and twist is so greatly increased as topractically avoid failure due to such load factors.

2 The normal loading on a rudder post is the force resulting from rudderaction when the latter is placed at an angle with respect to thedirection the ship is moving. As is well known, the rudder under theseconditions will have a certain centre of pressure at which the loadwhich changes the direction of the ship may be considered to beconcentrated. This centre of pres sure, in general, may be away from thehull of the ship by as much as ten feet (10) in a vertical direction andas much as ten feet (10) in a horizontal direction from the nearestavailable point of attachment of the supporting structurethe rudder orsternpost-to the ships hull. This force then tends to bend the stern orrudderpost at the line of the hull in a direction perpendicular to thelongitudinal axis of the ship and also tends to twist off therudderpost.

In view of the type of load which predominates in this type ofstructure, I have endeavored to introduced a metal section of acharacter calculated and best adapted to resist such a type of load. Tothis end, my invention comprises a wholly tubular rudder or sternpostwhose crosssectional contour of the main strength or main load-resistingmember may be a polygon of not less than four sides, and preferably isof cylindrical or circular contour.

The ideal section for resisting a torsional load is, of course, a tubewhich in addition is an effective member for resisting bending momentswhen it acts as a beam cantilevered out from t e hull. As analternative, in those cases where the bending load may predominate overthe torsional load, a square tube may be the choice of the designer. Asquare tube is more effective than a round tube for resisting bendingand is only slightly less effective from a torsion-resisting standpoint.In the use of a square tube, round fillets should be employed at allcorners internally of the same. 5,-

Between these two cross-sections lie a variety of polygonal sectionalcontours, any one of which may be equally adaptable and capable ofperforming the functions assigned to the round or square section rudderor sternpost. The usual 10. stream-lined, pear-shape, sternpost isdeficient in torsional strength and ineifective from a bendingstandpoint in the plane in which these rudder or sternposts deflect. Thetubular post of my construction can, of course, be stream-lined to 1'6,reduce the parasitic drag of the ship by means of properly shapedrelatively light gauge plates disposed forwardly of the same.

Various means may be employed for producing a tubular rudderpost withinthe scope of my in- 20 vention. For instance, it may be cast as a singlesection which will include the necessary upper and lower gudgeons orbearing supports for the rudder shaft. In order that the tubular portionof such rudderpost may be developed, the casting 25 may be cored andsimilar means may be employed to provide the openings in the gudgeons orbearing supports, such openings being subsequently finished as may benecessary or desirable; the openings of the gudgeons or supportsreceiving 30 the usual bronze bushings for the rudder shaft. In lieu ofthis arrangement, the sternpost may be made of plate, shaped to thedesired cylindrical or polygonal form. If polygonal, it may be made upof a plurality of plate sections or pre- 5 formed shapes Weldedtogether, and if a sectional form is employed, this will be thedesirable manner of producing the same. Polygonal shapes might beproduced by bending one or more sections to give the desired wallcontour. A cylin 40 drical structure may be developed from a singleplate bent into the desired contour and having its meeting edges weldedtogether.

In providing the desired gudgeons for a tubular rudder base orsternpost, the upper gudgeon may 45 be a separate tubular element weldedto the main body of the tubular post, while the lower gudgeon may be aseparate element welded in place, or it may be a cast section to whichthe tubular stern or rudderpost is attached as by welding and 50 thenbored through for the sake of lightness in the axis of the tubular sternor rudderpost. If desired, the lower opening of this bottom section, orthe bottom of a completely tubular post may be closed by aplate whichmay be welded in place. 5'

These and other features of my invention are more fully describedhereinafter, reference being had to the accompanying drawings, more orless diagrammatic in character, in which:

Figure 1 is a view in elevation of the stern of a ship showing theposition of my improved stern or rudderpost structure with respect tothe same.

Fig. 2 is a plan view of my improved stern or rudderpost structure on alarger scale.

Fig. 3 is a sectional elevation on the line III-III, Fig. 2.

Fig. 4 is a sectional View on the line IV-IV, Fig 3, looking in thedirection of the arrow at.

Fig. 5 is a plan view of a part of the structure, in section, on theline V-V, Fig. l, and

Fig. 6 is a sectional view illustrating a modified form of the mainstrength or load-resisting member of my improved structure.

The improved stern or rudderpost construction forming the subject of myinvention includes essentially a main strength or load-supportingelement, preferably of tubular cross-sectional contour, supported by andtied in with the plates of the hull of the ship at the stern of thesame. This element is indicated at I0, Figs. 1, 2, and 3, where it isshown as a section of a cylinder of proper dimensionslength anddiameter. This member is associated with and carries a gudgeon receivingthe rudder shaft. While, in some instances, a single gudgeon may beemployed, I prefer to employ two gudgeons, an upper gudgeon indicated atl I, and a lower gudgeon indicated at I2. These gudgeons may carry theusual bronze bushings in which the rudder shaft [3, carrying a rudderI4, is mounted, and such rudder may be of the usual stream-linedcontour, fore and aft. The upper gudgeon may be annularly recessed, asindicated at H to support the bronze bearing bushing.

The upper gudgeon l l is maintained in the desired position with respectto the main strength or load-supporting member by means of a cover platel5, welded thereto in any approved manner, the welds being indicated atx, and in addition this gudgeon may be welded to the member I at :c'.The cover plate is apertured at I for the passage of the rudder shaftand at l5 to gain access to the interior of the member H! to permitwelding. In Figs. 3 and 4, I have shown the lower gudgeon as a separatemember and, in the present instance, it is shown as being supported byplates l6 and I! of the shape more particularly shown in Fig. 5, saidplates having strap portions it and I! surrounding said gudgeonandwelded thereto, and portions welded to the member ID. The lower plateI! may extend beneath the tubular member II! in the manner indicated inFig. 3, such arrangement closing the bottom of the latter and preventingentrance of the sea. This lower gudgeon may be in the form of a castingor forging, secured to a member such as the member ID by welding, andthen bored through in the axis of said member for the sake of lightness,such member, of course, providing for the passage of the rudder shaft,and having the portion beneath the supporting member closed by suitablemeans. In addition, vertically disposed plates l8 and 19' may be securedto the upper gudgeon and the member Ill as by welding, being disposedover the plate lfi'to which they may also be welded.

The stern or rudderpost structure comprising the member land the upperand lower gudgeons H and i2 is tied in with the hull of the ship by aplate frame or shell which may consist of the angularly disposed sideplates 20, fore and aft transversely arranged plates 2| and 22, and theunderlying plates 23 and 24 which follow the line or plane of the hulland in addition to being welded together are interconnected with theplates of the latter, longitudinally and transversely, as indicated bythe rivet joints 25, Figs. 3 and 4. Bracing plates 26 may also bedisposed forwardly of the member Ill. These several plates of the frameor shell are reinforced or supported in proper relative position withrespect to the rudder or sternpost and the upper gudgeon II by means ofa series of tie plates 21, usually vertically arranged, and radiallydisposed with respect to the member I0 and the gudgeon H, as clearlyindicated in Fig. 2, such tie plates being welded to the walls of theshell and the other contacting parts of the structure, as indicated at1:, Fig. 2.

The member i 0 is preferably provided with internally disposed tieplates 30 and 3!, as clearly shown in Fig. 3, the upper plate 30following the line of the plates 23 which form part of the bottom ofsuch shell and additionally that much of the hull of the ship. Themember ID may be stream-lined forwardly by the employment of light gaugeplates 32, welded thereto and to the plates 23, as indicated at 112Figs. 3 and 5.

The member I0 illustrated in the drawings, tubular in form, may be asection of tubing of the desired weight and character, or it may be madeof a plate of proper Weight rolled or bent into shape and having itsmeeting edges welded together. It may be in the form of a casting orforging, hollow or solid, and, if solid, subsequent- 1y bored to providethe desired tubular contour, or it may be in the form of a tube having apolygonal cross-sectional contour and range from a four-sided polygon toone of many sidesjust short of or extending to a completely cylindricalform. If of polygonal shape-square, for instance-it may be built of apair of bent channel sections Ill as indicated in Fig. 6, weldedtogether at the lines r If a section of this type is employed, thecorner bends will have internally a radius not less than the thicknessof the metal making up the wall of such member. If the polygonallyshaped tube is developed from four or more plates, for instance, theinner corners will have rounded fillets welded to the walls of suchbuilt-up member.

I have employed the words tube and tubu lar in the foregoingspecification to indicate the hollow main load-supporting or strengthmember of my improved stern or rudder post structure. By tube andtubular is meant a hollow body having a cross-sectional contour whichmay range through polygonal contours (not less than four sides) to acylindrical structure, and it is to be so understood in the claims.

Various modifications may be made in the foregoing embodiment of myinvention without d'eparting from the spirit and scope thereof as setforth in the appended claims.

I claim:

1. The combination with the hull of a ship, of a rudder mountingcomprising a hollow load-resisting member connected to said hull in avertical position and terminating a short distance below the same, arudder, a shaft carrying the same, upper and lower bearing gudgeons forsaid shaft connected to said main load-resisting member, stay membersfor said load-resisting member framed into the hull fore and. aft,diagonally and laterally with respect to the'same,

a plate framed into the hull structure and forming a connection betweenthe upper gudgeon and the load-resisting member; said upper gudgeonlying substantially within the hull, and connections between the lowerbearing gudgeon and the load-resisting member.

2. The combination with the hull of a ship, of a rudder mountingcomprising a hollow load-resisting member connected to said hull in avertical position and terminating a short distance below the same, arudder, a shaft carrying the same, upper and lower bearing gudgeons forsaid shaft connected to said hollow load-resisting member, stay platesvertically disposed connected to said hollow load-resisting member foreand aft, diagonally and laterally with respect to the same and framedinto the hull of the ship, a continuous plate framed into the hullstructure and forming a connection between the upper gudgeon, theload-resisting member and said stay plates, and connections between thelower bearing gudgeon and said load-resisting member; said connectionsincluding a plate which underlies the hollow load-resisting member.

3. The combination with the hull of a ship, of a rudder, a shafttherefor, a supporting gudgeon for said shaft, a hollow load-resistingmember connected to said hull and terminating a short distance below thesame; said hollow member carrying said gudgeon and having wall sectionsdistributed at substantially the same radius around a central axis, andvertically disposed stay plates framed into said hull and disposed foreand aft, diagonally and laterally with respect to said hollow supportingmember and permanently connected thereto.

4. The combination with the hull of a ship, of a rudder, a shafttherefor, a supporting gudgeon for said shaft, a hollow load-resistingmember connected to said hull and terminating a short distance below thesame; said hollow member carrying said gudgeon and having a crosssectional contour in the form of a polygon of at least four sides, andvertically disposed stay plates framed into said hull and disposed foreand aft, diagonally and laterally with respect to said hollow supportingmember and permanently con nected thereto.

5. The combination, with the overhanging stern structure of a shipshull, of a rudderpost structure built into said overhanging sternstructure and comprising a fixed tubular member depending from andterminating a short distance below said overhanging stern structure, andrudder shaft supporting means carried by said tubular member anddisposed in parallel relationship therewith.

6. The combination, with the overhanging stern structure of a shipshull, of a rudderpost structure built into said overhanging sternstructure and depending from and terminating a short distance below thesame; said rudderpost structure comprising a main strength orload-resisting member of tubular form, and tubularruddershaft-supporting means carried by said load-resisting member anddisposed in parallel relationship therewith.

7. The combination, with the overhanging stern structure of a shipshull, of a fixed rudderpost structure including a member of tubularconstruction built into said overhanging stern structure and dependingfrom and terminating a short distance below the same; said tubularmember having portions of its walls symmetrically disposed with respectto a central axis, and rudder-shaft-supporting means carried by saidtubular member and disposed in parallel relationship therewith.

8. The combination with the hull of a ship having an overhanging sternportion, a rudder and a shaft therefor, of a rudder mounting framed intosaid hull; said rudder mounting comprising a fixed rudderpost and mainstrength or load-resisting member of tubular formation depending fromand terminating a short distance below the overhanging portion of thehull, and tubular means carried by said load-resisting member anddisposed in parallel and fixed relationship therewith for supporting therudder shaft.

9. The combination with the hull of a ship having an overhanging sternportion, a rudder and a shaft therefor, of a rudder mounting framed intosaid hull and comprising a fixed rudderpost or main strength member oftubular formation depending from and terminating a short distance belowthe overhanging portion of 1 the hull, and laterally disposed bearinggudgeons carried by said depending rudderpost and disposed in parallelrelationship therewith for supporting the rudder shaft.

10. In a rudder mounting for ships, the combination with the hull, arudder and a shaft carrying the same, of a hollow main load-resistingmember of tubular formation perpendicularly arranged with respect to thehorizontal cross axis of the hull and depending therefrom, a bearinggudgeon for said shaft carried by said tubular main load-resistingmember in parallel relationship therewith, and a frame supporting saidrudder mounting and including an upper plate connected to said tubularmain load-resisting member and disposed within the hull.

11. In a rudder mounting for ships having an overhanging stern portion,the combination with the hull, a rudder and a shaft carrying the latter,of a hollow main load-resisting member perpendicularly arranged withrespect to the horizontal cross axis of the hull and depending from andterminating a short distance below the overhanging portion of the hull,upper and lower bearing gudgeons for said shaft carried by said mainload-resisting member in spaced relation vertically and in parallelrelationship therewith, and a frame supporting said rudder mounting andincluding an upper plate connected to said loadresisting member and theupper bearing gudgeon and disposed within said hull.

EVERETT CHAPMAN.

